Synthetic-speech calculators

ABSTRACT

A synthetic speech calculator is provided which is capable of generating an audible sound signal which can be representative of keyed data, sequences of keyed data (and errors), processed data, the contents of a memory or the contents of a counter. The sound signal can be suppressed under certain specific circumstances or made soft in intensity. A synthetic-speech calculator includes the keyboard consisting of digit keys and function keys, a desired number of registers for storing information entered by the depression of selected ones of the digit keys, a read-only-memory for storing a large number of digital codes as sound quantizing information, counter means for specifying the address of the memory so as to take a specific digital code out of the memory, a digital-to-analog converter for converting the specific digital code taken out of the memory into an audible sound signal, and a loud speaker driven by the audible sound signal and producing an audible sound. There are provided means responsive to combinations of at least two sequentially operated keys of the keyboard for modifying the output condition of the audible sound, for example, volume, speed, etc. The synthetic speech calculator also has a selection key and multi-function keys, such as 7/sinθ. If the selection key is depressed followed by actuation of one of the multi-function keys, as audible sound indicative of the second function of the multi-function key is audibly generated, i.e., &#34;sinθ&#34; is audibly generated. If the selection key is not depressed prior to actuation of the multi-function key, an audibly sound indicative of the first function (7) is audibly generated. Similarly, the calculator will also develop an audible sound indicative of &#34;EQUAL&#34; if the following key sequence is actuated: a×b=, where a and b are numerals. The calculator will develop an audible sound indicative of &#34;TWO&#34; if the following key sequence is actuated: a×=. An audible sound indicative of &#34;THREE&#34; will be developed if the following key sequence is actuated: a×==.

This application is a divisional of copending application Ser. No. 874,950, filed on Feb. 3, 1978, now U.S. Pat. No. 4,185,169.

BACKGROUND OF THE INVENTION

The present invention relates to an improvement in a synthetic-speech calculator.

A synthetic-speech calculator is well known in the art of calculators. The prior art synthetic-speech calculators were capable of adjusting the volume of audible sounds through the use of a knob. Once the adjusting knob was set, the intensity of the audible sounds was constant in spite of the purpose of the audible sound. It is, however, desirable to the operator that audible sounds representative of calculation results be loudly produced while audible sounds concerning the entry of information from the keyboard be of lesser intensity. On the contrary, it is sometimes desirable that audible sounds be amplified only during the operation of keys in order to avoid errors in the entry of information while calculation results are visually provided. It may be more desirable to suppress the generation of audible sound in certain circumstances.

Meanwhile when producing audible sounds representative of the operation of a specific key, the operation of a next succeeding key should discontinue the generation of the previous audible sound. Accordingly, rapid operation of the keyboard causes a discontinuity in the production of audible sounds. If the operator is allowed to operate a specific key only after the delivery of audible sounds concerning the preceeding operated key, limitations on the speed of key operations would be unavoidable.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide an improvement in a synthetic speech calculator capable of overcoming all the disadvantages noted above.

According to one of the major features of the present invention in a synthetic-speech calculator, there is provided means responsive to combinations of at least two sequentially operated keys of a keyboard of the calculator for the purpose of modifying the output condition of audible sounds. The audible sound can represent keyed information, processed results of keyed information, the contents of a memory or the contents of a counter. The intensity of the audible sound can be varied depending on the type of data it represents. Various selection means are provided for indicating what the audible sound signal shall represent and for indicating which audible sound shall be loud and which shall be soft in intensity. The calculator comprises a keyboard consisting of digit keys and function keys, a desired number of registers for storing information entered by the depression of selected ones of the digit keys, a read-only-memory for storing a large number of digital codes as sound quantizing information, counter means for specifying the address of the read-only-memory so as to take a specific digital code out of the read-only-memory, a digital-to-analog converter for converting the specific digital code taken out of the memory into an audible sound signal, and a loud speaker driven by the audible sound signal and producing an audible sound.

In one aspect of the present invention, a modifying means is provided for modifying the intensity of audible sounds depending upon the results of the performances of decision means which decides whether the calculator now stands in the key entry state, the operation start state or the operation result outputting state. For example, the calculator has selectively operable four operating modes: the first where no audible sounds are produced; the second where audible sounds concerning both entered information and operation results are produced; the third where audible sounds concerning entered information are produced; and the last where audible sound concerning operation results are produced. The calculator, in addition, includes another mode selector thereby varying the intensity of the audible sounds from the loud speaker in accordance with the results from the decision means.

Some calculators may have double-multi-function keys. For example, function keys 7/sin , 8/cos and 9/tan have the functions of instructing digits "7", "8" and "9" and the functions of instructing operations "sin," "cos," and "tan," respectively. In this case however there are provided additional means for changing the audible sounds representative of the specific functions of a particular multi-function key. In the case where a calculator includes item counter means for counting the number of the depressions of keys, for example, + key and = key, there are provided means for producing audible sounds representative of the number of depressions of specific keys in response to a combination of at least two operated keys. In addition, for a calculator having one or more memories there are provided means for producing audible sounds representative of the contents of the memory or memories in response to combinations of at least two operated keys.

Therefore, in accordance with another aspect of the present invention, if a selection key "F" is actuated followed by the actuation of one of the multi-function keys, such as 7/sinθ, a first audible sound will be developed indicative of the second of the two multi-functions, such as "sinθ". If the selection key "F" is not actuated prior to actuation of one of the multi-function keys, such as 7/sinθ, a second audible sound will be developed indicative of the first of the two multi-functions, such as "7".

Similarly, in accordance with still another aspect of the present invention, if actuation of a first key "a", indicative of any numeral, is followed by actuation of the "x" key, indicative of multiplication, which is followed by actuation of another key "b", indicative of any numeral, a subsequent actuation of the equal key "=" will develop a first audible sound which is the "EQUAL" sound.

However, if actuation of the first key "a" followed by actuation of the "x" key, is not followed by actuation of the "b" key, a subsequent actuation of the equal key "=" will develop a second audible sound, which is the "TWO" sound. If the equal key "=" is again depressed, the sound "three" will be audibly developed.

Consequently, with respect to the last two embodiments of invention, described in the previous two paragraphs above, if a first key, such as the selection key "F" or the "b" key above, is actuated, and this is followed by at least one actuation of a second key, such as one of the multi-function keys (7/sinθ) or the equal key "=", a first audible sound will be developed indicative of either "sinθ" or "EQUAL", respectively.

However, if the first key is not actuated, i.e., if the "F" key or the "b" key is not actuated, prior to actuation of the second key, i.e., one of the multi-function keys (7/sinθ) or the equal "=" key, a second audible sound will be developed indicative of either "7" or "TWO", respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and novel features of the present invention are set forth in the appended claims and mode of operation will best be understood from a consideration of the following detailed description of the embodiments taken in conjunction with the accompanying drawings, wherein;

FIG. 1 is a plan view of a synthetic-speech calculator in the first embodiment of the present invention;

FIG. 2 is a block diagram of construction of the synthetic-speech calculator as shown in FIG. 1;

FIG. 3 is a block diagram of the second embodiment of the present invention;

FIGS. 4 through 6 are flow charts showing operation of the second embodiment of FIG. 3;

FIGS. 7 through 9 are diagrams showing the third embodiment;

FIGS. 10 and 11 are diagram showing the fourth embodiment of the present invention; and

FIGS. 12 and 13 are diagrams showing the fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1 view of the drawings, there is illustrated a perspective of a synthetic-speech calculator embodying the present invention in the first embodiment which includes a body 1, a display 2, a power switch 3, a loud speaker 4, a keyboard 5, a volume adjusting knob 6 and two mode switches 7 and 8. The speech synthesis technique is fully disclosed in many U.S. Patents, for example, U.S. Pat. No. 3,102,165, SPEECH SYNTHESIS SYSTEM to Genung L. Clapper and U.S. Pat. No. 3,398,241, DIGITAL STORAGE VOICE MESSAGE GENERATOR to Lyle H. Lee. The first switch 7 has selectively operable four modes N, V, V₁, and V₂ for controlling the generation and suppression of audible sounds: the first mode N where no audible sounds are produced; the second mode V where audible sounds are produced for both information entry and operation results; the third mode V₁ where audible sounds are produced for only information entry; and the fourth and last mode V₂ where audible sounds are produced for only operation results.

The second switch 8 has selectively operable three modes V₃, V₄, and V₅ for controlling the intensity of audible sounds; the first mode V₃ where audible sounds representative of keyed information are produced in a loud voice and ones representative of operation results are produced in a quiet voice; the second mode V₄ where audible sounds representative of keyed information are produced in a quiet voice and ones representative of operation results are produced in a loud voice; and the last mode V₅ (the so-called open state) where no changes are made in the intensity of audible sounds.

FIG. 2 illustrates a block diagram of the synthetic-speech calculator in the first embodiment of the present invention. A key board KK contains a family of digit keys 10K, a decimal point K, and a family of function keys FK (for example, an equal key = ). The calculator 1 comprises a calculation circuit or central processor unit CPU, an address counter AC, a read-only-memory ROM for storing a large number of voice quantizing digital codes, an END code detector for detecting end codes laden at the end of each of the one-word quantizing digital codes, a digital-to-analog converter D/A, an amplifier D, a loud speaker SP (corresponding to 4 of FIG. 1), a volume knob VR, a transistor TR, AND gates G₁, G₃, and G₄, an OR gate G₂ and a flip flop F₁ which is settable in response to a signal indicative of operations continued or an operation start signal OP and resettable in response to a signal Ko from any one of the key switches KK.

The flip flop F₁ is held in the set state from the beginning of operations through the depression of a second key and held in the reset state during the entry of keyed information or while any key except keys instructing operations to start is being depressed. In other words, operation results are derived while the flip flop F₁ is in the set state.

If it is desired to produce audible sounds indicative of any depressed key switch KK, the address counter AC specifies the initial address of its corresponding region of the ROM. The address counter AC selects desired steps so that the outputs (digital signals) Ro from the ROM are applied to the AND gate G₁ together with control signals and converted into analog signal via the digital-to-analog converter D/A. These analog signals are supplied via the amplifier D to energize the loud speaker SP. As described above, the end codes are laden at the end of each of the one-word quantizing digital codes. The end code detector JE senses the end codes and then resets the address counter AD. The address counter AD is incremented unless it is reset.

The calculation circuit CPU effects desired operations upon receipt of inputs from the key switches KK and allows the ROM to produce the voice quantizing digital codes in a manner similar to the generation of audible sounds indicative of keyed information. The amplifier is gain-adjustable. The transistor TR is connected to the fixed terminal RA of the volume variable resistor VR, which is under the control of a signal SS developed via the voice intensity controlling mode switch 8. When the signal SS turns on the transistor TR, a portion of the variable resistor VR is shunted, lowering the potential of the movable terminal of the variable resistor VR and thus the volume of audible sounds. In summary, upon the arrival of the control signal SS ("high" level) the transistor TR is turned on to lower the volume of audible sounds.

Assume now that the switch 8 is in the mode V₄. While producing audible sounds indicative of operation results, the control signal SS is at a high level to turn on the transistor TR so as to reduce the voice volume. Otherwise, the control dignal SS is at a low level so that the transistor TR is off to increase the voice volume. When the switch 8 is in the mode V₃, the reverse situation is experienced. Therefore, when the switch 8 is in the mode V₃, it is possible to produce audible sounds indicative of keyed information in a loud voice and ones indicative of operation results in a quiet voice. The mode V₄, on the other hand, makes audible sounds of keyed information quiet and ones of operations results loud. As long as the mode switch 8 is positioned at the mode V₅, the transistor TR always is off and the control signal SS has no effects.

Meanwhile, when the switch 7 is in the mode N, the OR gate G₂ is disabled so that the AND gate G₁ is disabled not to transmit the outputs Ro from the ROM to the digital-to-analog converter D/A. While the AND gate G₁ decides whether audible sounds are produced, the output from the gate G₂ may control the power source of the amplifier D.

If the switch 7 is in the mode position V, the OR gate G₂ is enabled unconditionally to produce audible sounds. If the switch 7 is changed to the mode position V₁, the AND gate G₃ is on. Since the AND gate G₃ receives another input from the set output of the flip flop F₁, audible sounds of only keyed information are eventually produced. The switch 7 in the mode position V₂ turns on the gate G₄. Since the gate G₄ receives as another input the reset output of the flip flop F₁, audible sounds of only operation results are produced. In this manner, audible sounds are changed in intensity or inhibited in accordance with the internal states of the calculator.

FIGS. 3 through 6 show the second embodiment of the present invention which is capable of discontinuing the generation of audible sounds when manual depressions of keys are carried on very quickly. The components in the second embodiment of FIGS. 3 through 6 are given the same numbers as in FIGS. 1 and 2 wherever possible in order to point out the close relationship.

In the given example, key signals from the keyboard are introduced into a buffer NB via an encoder EC. A random-access-memory RAM contains a given number of digit registers with an input terminal Ii, an output terminal Oi and an address counter MAD. This is depicted as having a six-digit capacity in FIG. 3. The keyed numerical information is transferred from the buffer NB to the RAM in accordance with the address specified by the counter MAD when a microinstruction 2 is developed. A shift circuit SHR is adapted to shift the contents of the memory RAM and more specifically effect one-digit left shift thereon upon the development of the memory RAM.

A decision circuit FK of FIG. 3 determines whether any or all the keys of the keyboard has been actually operated, while a second decision circuit J₁₀ determines whether any of the digit keys has been actually operated.

A digit register C along with an adder/subtractor AD₁ counts the number of the digits that have been loaded into the RAM. The register C and the adder AD₁ form an adder circuit which effects addition of "1" to the contents of the register C upon the development of a microinstruction 3 whenever each digit of information is entered into the RAM.

Upon the receipt of a microinstruction 18 a register D receives the contents of the register C. A microinstruction 7 renders the RAM ready for sequential delivery of the contents of register C with aid of the address counter MAD. In addition, the register D and the adder/subtractor AD₁ form a subtractor circuit in response to a microinstruction 6 . In other words, the contents of the register D are "1" subtracted each time information of the RAM is derived as an audible sound output. Microinstructions 4 and 5 are signals that reset the registers C and D.

A decision circuit JD determines whether the contents of the register D are zero's, and the affirmative answer from the decision circuit CD indicates that the delivery of all audible sound outputs from the RAM has been completed.

The voice quantizing digital codes are stored in preselected order in the ROM, for example, "ichi (one)," "ni(two)," "san (three)," "yon (four)," etc.

As stated above, the ROM has the address counter AC which is responsive to a microinstruction 9 developed when information via a buffer NB is entered thereto. The address counter AC specifies the initial address of the respective regions of the ROM. The counter AC and an adder AD₂ form an adder circuit in response to the development of a microinstruction 15 . After specifying the initial address of the respective regions, the address counter AC keeps on addressing sequentially the ROM.

As in FIG. 2, the decision circuit JE senses the end codes and then discontinues the increment of the address counter AD. A microinstruction is a reset signal for the address counter AC. Similarly, the digital-to-analog converter D/A is connected to an output terminal of the ROM. A low-pass filter LPE, and a speaker driver DS are interposed between the digital-to-analog converter D/A and the loud speaker SP. A speaker control PS includes a flip flop FV to control a power supply to the loud speaker SP. The flip flop FV is set upon a microinstruction 10 and reset upon a microinstruction 11 , the set output SFV being connected to the control PS.

A flip flop F is placed into the set state in response to a microinstruction 13 when information is entered into the RAM. A decision circuit JF senses the set state of the flip flip F. A microinstruction 14 resets the flip flop F.

A flip flop G is set in response to a microinstruction 16 while producing audible outputs, the set state thereof being sensed by a decision circuit JG. A microinstruction 17 resets the flip flop G.

In FIG. 4, events in a sequence of operation are labeled n₁ through n₂₉ and microinstructions are labeled 1 through 18 . The microinstruction 1 through 18 correspond to those as shown in FIG. 3.

If no key is actually operated, the decision JK will not sense the depression of any keys in the step n₁. The step n₂ is reached where the decision JG does not sense the flip flop G in the set state (i.e., the audible output is being produced), thereby advancing to the next step n₃. At this moment the decision JF in the step n₃ does not sense the set state of the flip flop F (i.e., information is being entered into the RAM). The step n₁ is restored. In this manner, a loop of n₁ →n₂ →n₃ →n₁ is recirculated when no key is operated.

Thereafter, if any key is depressed, operation is skipped to the step n₄ where the decision J₁₀ determines whether that depressed key is a digit key or a function key. If the digit key is sensed, the key signal is encoded via the encoder EC and introduced into the buffer NB in the step n₅. Under the circumstances the microinstruction 1 is developed to enable the shift circuit SHR to effect left shift of the RAM. Then, the step n₆ is reached.

The microinstruction 2 is developed so that information is transferred from the buffer NB to the input terminal Ii and the address counter MAD is given an address code N₁ to provide access to the first digit position M₁ of the register RAM, loading the information into M₁ of the RAM.

During the next succeeding step n₇ the microinstruction 3 is developed so that the adder circuit is established between the register C and the adder/subtractor AD₁ to add "1" to the contents of the register C. In this case the register C is incremented from "0" to "1". The step n₂₉ is then reached. Upon the development of the microinstruction 18 the contents of the register C are transferred to the register D. At this time the register C keeps on storing information.

In the step n₁₁ the decision JG never senses the set state (i.e., the audible output are being produced) of the flip flop G. The step n₂₂ becomes operative where the decision JD senses that the register D does not assume "0" because the register D has already been laden with a "1".

Thereafter, in the step n₂₄ the microinstruction 13 is developed to set the flip flop F, reverting to the step n₁. The decision JE senses the flip flop F in the set state.

If no key is depressed after returning to the step n₁, the step n₂ is reached where the decision JG does not sense the set state of the flip flop G. In the step n₃ the decision JE determines that the flip flop F is in the set state, advancing to the step n₁₂.

In the step n₁₂ the microinstruction 7 is developed so that the address counter MAD is set in accordance with the contents of the register D, firstly specifying the first digit position of the RAM. In other words, "1" stored in the register D menas "1" stored in the address counter MAD, specifying the address of the first digit position of the RAM. Then, the step n₁₃ follows where information stored in the first digit position of the RAM is shifted to the buffer VB in response to the microinstruction 8 .

Afterward, in the step n₁₅ the microinstruction 16 is developed to set the flip flop G. At this time the decision JG senses the flip flop G in the set state. The step n₁₆ follows where the contents of the buffer VB specify the address counter via the microinstruction 9. The address counter AC provides access to the initial address of the respective regions of the ROM corresponding to information stored in the RAM.

The microinstruction 10 is developed to set the flip flop FV in the step n₁₇. The control PS starts supplying the speaker driver SD with power in response to the set output SFV of the flip flop FV. In the next step n₁₈ the decision JE does not sense the end code because the address counter AC has just specified the initial address of the respective regions, followed by the step n₂₆. A delay action which will be described with respect to FIGS. 5 and 6, is carried through between the steps n₂₆ and n₂₅. In the following step n₂₅, the microinstruction 15 is developed to permit the adder AD₂ to add "1" to the contents of the address counter AD, specifying the next succeeding address within that region. In the event that no key is depressed after reterning to the step n₁ again, the step n₂ is carried through where the decision JG senses the set date of the flip flop G, followed by the step n₁₈. The continued step n₂₆ →n.sub. 25 →n₁ are effected in advance of the appearance of the end code at the decision JE. Therefore, circulation of the steps n₁ →n₂ →n₁₈ →n₂₆ →n₂₅ →n₁ provides access to the overall region.

The digital codes are taken sequentially out of the ROM, by addressing of the address counter AD, starting with its initial address. These digital codes are converted via the digital-to-analog converter D/A, producing audible sounds via the low-pass filter LPF, the speaker driver SD and the loud speaker SP.

Since in this case the address counter AC achieves the addressing in accordance with a different digit of the RAM, the region "ichi" ("one" in English) of the ROM is allocated when the addressing is by numeral information "1" and the one "ni" ("two" in English) is allocated when the addressing is by numeral information "2". If the end code is derived from the regions, the decision JE is active moving forward to the step n₁₉.

In the step n₁₉ the microinstruction 11 is developed to force the flip flop FV into the reset state, ceasing a power supply to the driver SD. The step n₂₀ is effected to develop the microinstruction 17 and reset the flip flop G. The step n₂₁ follows where the address counter AD is reset upon the development of the microinstruction 12. Subsequently, the adder/subtractor AD₁ serves to subtract "1" form the contents of the register D upon the microinstruction developed. As a results, the register D bears "0".

After that, the decision JD in the step n₂₂ senses "0" in the register D (determining that the audible sound corresponding to the digits keyed via the keyboard have all been completed), moving toward the step n₂₃. Upon the receipt of the microinstruction 14 the flip flop F is reset, followed by the step n₂₇ where the register C is reset by the microinstruction. In the step n₂₈ the register D is reset by the microinstruction 5, restoring to the step n₁.

The above described "1" subtraction is necessarily required in the step n₁₄ after completing the access to the overall region. The decision D in the step n₂₂ determined whether audible outputs for all the keyed digits have been produced. This is accomplished by the detection of the register D in the "0" state.

A loop n₁ →n₂ →n₃ →n₁ is circulated if no key is operated after returning back to the step n₁. When the second depression of a different or same key is viewed, the procedure is repeated in the same manner as for the previous key depression.

Since in this case the register RAM is left shifted in the step n₅, numeral information by the first key depression is loaded into the second least significant digit M₂ and numeral information by the second key depression is loaded into the least significant digit M₁. While the addressing of the address counter AD is effected by "1" in the register D in the step n₁₂, the least significant digit M₁ of the RAM specifically sets the address counter AD during the steps n₁₃ through n₁₆, specifying the corresponding region of the ROM to produce audible sounds.

Attention is directed to FIGS. 5 and 6 of the drawings showing the delay action in the step n₂₆. The detailed step n₂₆ consists of three steps n₂₆, n₂₆ " and n₂₆ "' : the first step n₂₆, whereby a specific constant n is loaded into a register H; the second step n₂₆ " whereby "0" in the register H is determined; and the last step n₂₆ "' whereby a subtractor AD₃ is effective on the register H. "0" in the register H sensed leads to the step n₂₅. In other words, the microinstruction 20 is developed to lead the specific constant n into the register H in the first step n₂₆ '. A decision JH in the step n₂₆ " determined whether the register H bears O's. The register H does not bear S's in the initial state, resulting in that the microinstruction 21 is developed to effect "1" subtraction in the step n₂₆ "'. Then, the step n₂₆ " is returned to the O's decision. In this manner, a loop n₂₆ "→n₂₆ "'→n₂₆ " is repeated until the register H comes to the "0" state.

Assume that any function key is operated under these circumstances. The procedure is started with the step n₁ and moved toward the step n₄. The decision J₁₀ senses no digit key, followed by the step n₈ where the microinstruction 4 is developed to reset the register C. Then, the step n₉ is carried through to develop the microinstruction 5 and reset the register D, moving forward the step 31. The flip flop FV is reset in the step n₃₀ and the flip flop G is reset in the step n₃₁ and the address counter AD is reset either in the step n₃₂. Subsequently, a control routine is effected for the function key depressed in the step n₁₀, restoring to the step n₁. For this reason, when a specific function key is operated, the delivery of audible sounds is forcedly inhibited.

The second key is depressed quickly on the way to produce audible sounds indicative of the first depressed key. The depression of the first key allows the advancement of a sequence of the steps n₁ →n₄ →n₅ →n₆ →n₇ →n₂₉ →n₁₁ →n₂₂ →n₂₄ → n₁ → n₂ → n₃ →n₁₂ →n₁₃ →n₁₅ →n₁₆ →n₁₇ → n₁₈ →n₂₄ →n₂₅ →n₁, thereby providing sequentially the designated region of the ROM.

If the second key is depressed while producing audible sounds, the steps are changed from a loop n₁ →n₂ →n₁₈ →n₂₆ →n₂₅ →n₁ to a loop of n₁ → n₄ →n₅ →n₆ →n₇ →n₂₉ →n₁₁. The decision JG is the step n₁₁ senses the flip flop G in the set state to establish a loop the steps n₂₆ →n₂₅ →n₁ →(n₁ → n₂ →n₁₈ →n₂₆ →n₂₅ →n₁).

In summary, in the event that the second or third depression is carried through while producing audible sounds indicative of the first depressee key, that audible sound is discontinued so that information indicative of the second or third key is first loaded into the RAM and the audible sounds are produced again.

Because in this case a loop of the steps n₁₈ →n₂₆ →n₂₅ is not passed even upon the depression of the second or third key, the address counter AC is not incremented and keeps on specifying the same address. Under the circumstances the delay action is intervened to avoid distortions in the waveform of audible sounds, ensuring normal audible sounds.

FIGS. 7 through 9 show the third embodiment where the present invention is applied to calculators having multi-function keys. The components in the embodiment in FIGS. 7 through 9 are given the same number as in FIGS. 1 through 6 wherever possible in order element 15 in FIG. 7 designates a two-function key, for example 7/sin, 8/cos and 9/tan which is different from the normal single-function keys. In other words, the two-function keys have the functions of introducing digits "7", "8", and "9" and the functions of introducing operations "sin", "cos," and "tan." A function selection key F is provided for function selection of the two-function keys. When any of the multi-function keys is depressed in the clear or ready state or calculation end state of the calculator, any of the digits "7" through "9" is specified. After the depression of the function selection key F, the multi-function keys can specify any of the operations "sin" through "tan". A sound reproduction key K is provided.

A flip flop F₁₁ of FIG. 9 senses the depression of the function selection key F and is placed into the set state in response to depression of the selection key F and into the reset state in response to depression of all the remaining keys. A key output Ko is derived whenever any of the keys is depressed.

Provided that the multi-function key 7/sin is depressed under the condition that the selection key F has not been operated and the flip flop F₁₁ is in the reset state, a family of logic gates G₁₁ will be active to load the address counter AC with the initial address of the region of the ROM containing digital codes "nana" (in English seven). The same is applicable to the other multi-function keys 8/cos and 9/tan . By specifying the region "nana" of the ROM, audible sound "nana" is produced via the speaker SP driven by Ro. The decision JE senses the end code positioned at the end of the sound quantizing digital codes. When the end code is detected the address counter AC is reset to suppress the generation of audible sounds. It will be noted that the address counter AC is not self running as long as it is held in the reset state.

If the multi-function key 7/sin is depressed after the depression of the function selection key F as viewed from FIG. 8, line (4), F₁₁ is set to turn on a gate C₁₂ so that the output from the multi-function key 7/sin specifies the initial address of the region of the ROM containing the sound quantizing digital codes "sain" (sin in English). Therefore, audible sound "sain" is produced in response to the depression of the multi-function key 7/sin after the depression of the selection key F forces the F₁₁ into the reset state.

The difference between the normal single-function keys and the two-function keys should be recognized as in the case of power calculations of FIG. 8, lines (2) and (3). A flip flop F₁₂ of FIG. 9 determines whether the = key is depressed after the depression of the X key. The depression of the × key specifies the initial address of the region of the ROM containing the quantized sound "kakeru" (multiply in English) via AC and placed the flip flop F₁₂ into the set state. While F₁₂ is reset upon the depression of any keys rather than the = key following the × key, the = key when depressed sets the flip flop F₁₂.

When the F₁₂ is in the reset state, the depression of the = key makes a gate G₁₃ operative to specify the region of the ROM containing sounds "ikoru" (equal in English). The depression of the = 0 key under the set state of the F₁₂ turns on a gate G₁₄ to load the first bit CO₁ of a counter CO with "1" and increment one step a binary counter CB. The binary counter CB will be reset (for example, "0000") upon by a gate G₁₅ the depression of any other keys than the = key.

The binary counter CB bears "0001" is response to the depression of the keys × and = , which instructs square calculations. In decoding CB via a decoder DC, the output of the decoder DC is connected to AC in a manner to specify the initial address of the region of the ROM containing audible sounds "ni" ("two" in English). In this manner, the gate G₁₄ is turned on in response to the = key of the depressions × and = with the result that CO₁ =1 and CB=0001.

A gate G₁₇ is turned on so that the output of the decoder DC specified the region of the ROM containing the voice quantizing digital codes "ni" to produced audible sounds "ni". Then, JE=1 upon the appearence of the end code to reset the address counter AC. In order to produce audible sounds "jyo" (square in English), a delay circuit DD is provided to lodge an appropriate pause between the audible sounds "ni" and "jyo". The output of the JE is delayed via the delay circuit D and entered into a shift control SHC for the counter CO. The result is that "1" in the CO₁ is shifted to the second bit with CO₂ =1. The relationship CO₂ =1 permits the address counter AC to specify the initial address of the region "jyo." That is, the depression of the keys × and = produces the audible sounds "ni" and "jyo."

Further depression of the = key (FIG. 8, line (3)) enables the gate G₁₄ so that CB is incremented to "0010" and the counter CO bears "01". Therefore, the output of the decoder DC corresponds to "0010" in CB. A signal is applied to AC via the gate G₁₇, specifying the initial address of the region of the ROM containing the digital codes "san" (three in English). After producing sounds "san," the sounds "jyo" is produced.

FIGS. 10 and 11 show the fourth embodiment which produces audible sounds indicative of the contents of an item counter. Generally, the primary object of an item counter is to count the number of depressions of a specific key, for example, + key or + key.

A mode selector 20 has three selectively operable modes N, A₁ and A₂ : the first mode N where the item counting is not required; the second mode A₁ where the item counter is carried through while the counts of the counter is provided visually but not acoustically; and the third mode A₂ where audible sounds indicative of the contents of the item counter are produced in accordance with the present invention. A keyboard includes a count output key 16.

In FIG. 11, numerical registers W and Y contained within the RAM store information processed by the processor CPU, the contents of one of the registers W being automatically displayed on a display DSP. A register X consists of two digit positions X₁ and X₂ and is able to store the counts of 1 through 99. A circuit labeled CUC is provided to increment one step of the contents of the register X in response to the development of a microinstruction 31 . A clear circuit CCL is provided to clear up the register X and whenever the switch 20 is in the mode N the register X is cleared. AND gates G₃₁ -G₃₃ and an OR gate G₂₄ are included. A signal CD₁₀ permits the address counter AC to specify the initial address of the region of the ROM containing sounds "Jyu" (ten in English). FIGS. 12 and 13 show the fifth embodiment wherein the present invention is applied to a memory calculator. The memory provided calculator of FIG. 12 has a memory recall key 21 and a specific key 22. In FIG. 13 there are at least three memories M₁, M₂ and M₃. Gates G₅₁ and G₅₂ are provided for selection of any one of the memories M₁, M₂ and M₃. A gate G₅₃ is provided for directing operation results toward the display register W or a selected one of the memories M₁, M₂ and M₃. A buffer VM is effective in producing audible sounds indicative of the contents of any one of the memories M₁, M₂, M₃, and stores at the most significant digit position thereof coded decimal point information VMd. SCO denotes a circuit for subtracting "1" from the contents of the counter CO. A coincidence circuit JD determines whether the contents of the counter CO is equal to the decimal point information VMD in the register VM. When the counter CO shows "1", the least significant digit information of the VM register is entered into the buffer register BC. A timing signal generator PC provides information, the timing signals being applied to an AND gate G₅₅ together with the output of the VM register. Audible sounds indicative of the contents of a particular one of the memories M₁, M₂ and M₃ are produced in the substantially same manner as in the foregoing embodiments.

As used in the foregoing description, "key in a keyboard" is intended to mean not only any keys contained within a keyboard but also any mode selectors generally disposed apart from the keyboard for purposes of the present invention.

While only certain embodiments of the present invention have been described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as claimed. 

We claim:
 1. A synthetic speech calculator having a keyboard, said keyboard including a first key and a second key, comprising:audible sound signal generating means responsive to actuations of said first and second key for producing a first audible sound signal in response to an actuation of said first key followed by at least one actuation of said second key and for producing a second audible sound signal in response to at least one actuation of said second key; and audible sound generating means responsive to said first audible sound signal and said second audible sound signal from said audible sound signal generating means for generating a first audible sound in response to said first audible sound signal and for generating a second audible sound in response to said second audible sound signal.
 2. A synthetic speech calculator in accordance with claim 1 wherein said second audible sound signal is produced in response to the absence of actuation of said first key followed by actuation of said second key.
 3. A synthetic speech calculator in accordance with claim 2 wherein a third audible sound signal is produced in response to the absence of actuation of said first key followed by at least two actuations of said second key.
 4. A synthetic speech calculator in accordance with claim 3 wherein said first audible sound signal is produced in response to the following sequence of key actuations:

    a×b=,

where a represents actuation of a numeral key, x represents actuation of a key indicative of multiplication, b represents actuation of a numeral key and further represents actuation of said first key, and = represents actuation of an equal key and further represents actuation of said second key.
 5. A synthetic speed calculator in accordance with claim 4 wherein said second audible sound signal is produced in response to the following sequence of key actuations:

    a×=,

where = represents actuation of said equal key and further represents actuation of said second key.
 6. A synthetic speech calculator in accordance with claim 5 wherein said third audible sound signal is produced in response to the following sequence of key actuations:

    a×==,

where == represents two sequential actuations of said second key.
 7. A synthetic speech calculator in accordance with claim 2 wherein said first key comprises a function key, said second key including a multi-function key representing a numeral and a function, said audible sound signal representative of said function being produced in repsonse to actuation of said function key followed by actuation of said multi-function key, said audible sound signal representative of said numeral being produced in response to the absence of actuation of said function key followed by actuation of said multi-function key.
 8. A synthetic speech calculator in accordance with claim 7 wherein said audible sound signal generating means comprises:flip-flop means responsive to actuations of said function key for generating a set signal in response to actuation of said function key and for generating a reset signal in response to actuation of said multi-function key without an actuation of said function key; gate means responsive to said set and reset signals from said flip-flop means for generating a frist gated signal in response to said set signal from said flip-flop means and a second gated signal in response to said reset signal from said flip-flop means; memory means for storing sound related digital codes therein; and address counter means responsive to the gated signals from said gate means for storing address information therein corresponding to said first gated signal and said second gated signal from said gate means, said address information from said first gated signal selecting one of said sound related digital codes in said memory means, said address information from said second gated signal selecting another of said sound related digital codes in said memory means, said memory means generating said first audible sound signal associated with said one of said sound related digital codes, said memory means generating said second audible sound signal associated with said another of said sound related digital codes.
 9. A synthetic speech calculator in accordance with claim 3 or 6 wherein said audible sound generating means comprises:flip-flop means responsive to an actuation of said first key followed by an actuation of said second key for generating a set signal in response thereto AND gate means responsive to said set signal from said flip-flop means and to an actuation of said second key for generating an output signal in response to said set signal and to said actuation of said second key: counting means responsive to said output signal from said AND gate means for counting the number of actuations of said second key in the presence of said set signal, said counting means generating a plurality of counting signals, each of said plurality of counting signals respectively corresponding to each of the sequential actuations of said second key; address counter means responsive to said plurality of counting signals for storing a plurality of address information, each of said plurality of address information respectively corresponding to said plurality of counting signals; and memory means for storing sound related digital code signals therein, each of said plurality of address information addressing different ones of said sound related digital code signals in said memory means, said memory means generating a plurality of said audible sound signals corresponding to said different ones of said sound related digital code signals. 